What was found
AFTER MX FOR APU BLEED AIR SMOKE IN CABIN, WE RAN APU 10 MINUTES, BLEED AIR ON FOR 5 MINUTES, SMELLED SMOKE, THEN OBSERVED BLUE SMOKE COMING OUT FLOOR AISLE VENTS. SHUTDOWN IMMEDIATELY. TROUBLESHOOTING PERFORMED AND FOUND THAT THE APU WAS LEAKING OIL INTERNALLY. REMOVED DEFECTIVE APU AND INSTALLED A SERVICEABLE APU. ACCOMPLISHED ALL REQUIRED LEAK AND OPS CHECKS WITH SATISFACTORY RESULTS. WORK PERFORMED IAW AMM CH-49-11-00.